Grand Haven gets deadly rip current sensor

Technology used for years to forecast hazardous weather conditions may soon be applied to predicting dangerous rip currents in Lake Michigan.

The National Oceanic and Atmospheric Administration recently installed a device on the Grand Haven pier that monitors lake currents in front of the popular Grand Haven State Park. The device, called an Acoustic Doppler Profiler, uses sonar to measure the strength of currents along the beach and pier.

Researchers hope the device produces data that helps meteorologists better predict when rip currents are likely to be present at Great Lakes beaches.

"It should help the National Weather Service improve their forecasts of rip currents," said David Schwab, an oceanographer at NOAA's Great Lakes Environmental Research Laboratory in Ann Arbor. "It won't be a warning system, though."

Rip currents funnel water near beaches into deeper areas of the lake, creating a vacuum-like effect that can pull swimmers away from the shoreline and keep them from swimming back to safety. The currents can be present at any time, but are most severe when strong west winds buffet area beaches.

The Grand Haven project marks the first time the Doppler device has been used to gauge the strength of currents along Great Lakes beaches. Schwab said researchers selected the Grand Haven beach because rip currents there have caused drownings in recent years.

The 2003 death of Grand Haven resident Andy Fox, one of several people who has drowned over the years while swimming near the pier, prompted a campaign to educate swimmers about the dangers of rip currents in Lake Michigan. One aspect of that campaign was the placement of a large sign on the Grand Haven pier that shows swimmers how to escape a rip current.

National Weather Service meteorologist Bob Dukesherer said many swimmers underestimate the power of rip currents, particularly along solid piers and breakwalls. The structures disrupt natural lake currents, concentrating energy and fueling powerful rip currents.

"On days with high waves, you don't want to be swimming near piers," Dukesherer said. "We've seen very strong swimmers get caught in rip currents next to the Grand Haven pier and they couldn't get out."

The National Weather Service in Grand Rapids posts rip current advisories on its Web site as part of its hazardous weather outlook, which includes everything from high winds to heavy rainfall events.

The weather service hopes to begin issuing advisories specifically for rip currents at West Michigan beaches by next month, Dukesherer said. A similar forecasting system is expected to be in place for all the Great Lakes by next summer.

The Acoustic Doppler Profiler is stationed near Grand Haven's south pier, several feet below the surface of Lake Michigan. Similar devices are used to monitor river currents.

The device sends out sonar beams that measure the strength of lake currents every six feet. The result is a graphic that gives a bird's eye simulation of where currents are strongest. Those images can be viewed on NOAA's Web site: www.glerl.noaa.gov/res/glcfs/gh.

Schwab said measuring currents along the lakeshore is difficult, even with sonar technology. He said researchers fear high waves could damage or destroy the monitoring device.